Magnetically coupled safety valve with satellite inner magnets

ABSTRACT

A safety valve can include multiple magnetic devices reciprocably disposed in respective longitudinally extending chambers, and a another magnetic device magnetically coupled to the first magnetic devices. The first magnetic devices may be circumferentially spaced apart and encircled by the second magnetic device. Another safety valve can include multiple longitudinally extending chambers and multiple magnetic devices. Each of the magnetic devices may be reciprocably disposed in a respective one of the chambers, and the magnetic devices may be attached to an operating member of the safety valve.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of prior application Ser. No.11/618489, filed on 29 Dec. 2006. The entire disclosure of the priorapplication is incorporated herein by this reference.

BACKGROUND

This disclosure relates generally to equipment utilized and operationsperformed in conjunction with a subterranean well and, in an exampledescribed below, more particularly provides a magnetically coupledsafety valve with satellite magnets.

Operation of a safety valve using magnetic coupling across a pressureisolation barrier has been described in U.S. Pat. No. 6,988,556. Theentire disclosure of this prior patent is incorporated herein by thisreference.

Space is always limited in wellbores and higher pressure ratings arecontinually needed. Therefore, it will be appreciated that improvementsare continually needed in the art of magnetically coupled safety valves.

SUMMARY

In the disclosure below, a safety valve is provided which bringsimprovements to the art. One example is described below in whichmultiple “satellite” magnetic devices attached to an operating member ofthe safety valve are positioned between a flow passage and an outermagnetic device. Another example is described below in which thesatellite magnetic devices displace within a pressure bearing wall ofthe safety valve.

In one aspect, a safety valve for use in a subterranean well is providedto the art. In one example described below, the safety valve can includemultiple magnetic devices reciprocably disposed in respectivelongitudinally extending chambers, and a another magnetic devicemagnetically coupled to the first magnetic devices. The first magneticdevices are circumferentially spaced apart and are encircled by thesecond magnetic device.

In another aspect, a safety valve is disclosed which, in one example,can include multiple longitudinally extending chambers and multiplemagnetic devices. Each of the magnetic devices is reciprocably disposedin a respective one of the chambers, and the magnetic devices areattached to an operating member of the safety valve.

These and other features, advantages and benefits will become apparentto one of ordinary skill in the art upon careful consideration of thedetailed description of representative examples below and theaccompanying drawings, in which similar elements are indicated in thevarious figures using the same reference numbers.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a representative partially cross-sectional view of a wellsystem which can embody principles of this disclosure.

FIG. 2 is an enlarged scale representative cross-sectional view of aportion of a safety valve which can embody principles of thisdisclosure.

FIG. 3 is a representative cross-sectional view of the safety valve,taken along line 3-3 of FIG. 2.

FIG. 4 is a representative cross-sectional view of an actuator portionof the safety valve.

FIG. 5 is an enlarged scale representative side view of a satellitemagnetic device of the safety valve.

FIG. 6 is a representative cross-sectional view of another configurationof the safety valve.

FIGS. 7-9 are representative quarter-sectional views of additionalarrangements of magnetic devices in the safety valve.

FIGS. 10A-G are representative cross-sectional views of anotherconfiguration of the safety valve.

DETAILED DESCRIPTION

Representatively illustrated in FIG. 1 is a well system 10 which canembody the principles of this disclosure. A safety valve 12 isinterconnected in a tubular string 14 as part of a production assembly16 positioned in a wellbore 20. A line 18 is used to control operationof the safety valve 12 from a remote location, such as the earth'ssurface, a subsea facility, etc.

The line 18 may be a hydraulic, electrical, optical, or other type orcombination of line(s). Alternatively, operation of the safety valve 12may be controlled from the remote location using telemetry, such aselectromagnetic, acoustic, pressure pulse, or other type of telemetry,in which case the line 18 may not be used.

The safety valve 12 is used to selectively permit and prevent flow offluid through a flow passage 22 (not visible in FIG. 1, see FIG. 2) ofthe tubular string 14 which extends through the safety valve.Specifically, in emergency situations the safety valve 12 is used toclose off the passage 22 and thereby prevent uncontrolled flow ofhydrocarbons to the surface via the tubular string 14.

However, it should be clearly understood that the well system 10 asdepicted in FIG. 1 and described herein is only one of the manyapplications for the principles of this disclosure. A large variety ofdifferent well systems and other applications may incorporate theprinciples of this disclosure, and so it will be appreciated that thisdisclosure is not limited in any respect to the details of the wellsystem 10.

Referring additionally now to FIG. 2, an enlarged scale schematiccross-sectional view of a longitudinal portion of the safety valve 12 isrepresentatively illustrated. In this view it may be seen that thesafety valve 12 includes a closure assembly 24 which is operated bydisplacing an operating member 26 to selectively permit and prevent flowthrough the passage 22.

The closure assembly 24 in this embodiment includes a flapper 28 whichrotates about a pivot 30 relative to a sealing surface 32 formed on aseat 34. As depicted in FIG. 2, the operating member 26 is in itsupwardly displaced position and the flapper 28 sealingly engages thesealing surface 32 to prevent flow through the passage 22.

However, when the operating member 26 is displaced downward, theoperating member will contact the flapper 28 and rotate the flapperdownward about the pivot 30, thereby permitting flow through the passage22. As described more fully below, a magnetic coupling is used todisplace the operating member 26 between its upwardly and downwardlydisplaced positions to thereby selectively prevent and permit flowthrough the passage 22.

The operating member 26 is of the type known to those skilled in the artas a flow tube or opening prong. The operating member 26 may includefeatures in addition to those depicted in FIG. 2, such as aspring-loaded nose, etc. In addition, other types of operating membersmay be used, without departing from the principles of this disclosure.

Other types of closure assemblies may also be used in place of theclosure assembly 24. For example, a ball valve type of closure assemblycould be used in place of the flapper type closure assembly 24. Thus, itshould be clearly understood that the principles of this disclosure arenot limited in any manner to the details of the safety valve 12described herein.

The operating member 26 and closure assembly 24 are contained within agenerally tubular housing 36. Although the housing 36 is schematicallydepicted in FIG. 2 as being a single component of the safety valve 12,it will be appreciated that the housing could instead be made up ofmultiple interconnected components to thereby form a housing assembly.

The housing 36 includes a pressure bearing wall 38. In this embodiment,the wall 38 is exposed to pressure in the wellbore 20 external to thehousing 36 when used in the well system 10, and the wall is exposed topressure in the passage 22. Thus, the wall 38 is a pressure isolationbarrier which resists any pressure differential between the passage 22and the wellbore 20 external to the safety valve 12.

Multiple circumferentially spaced and longitudinally extending chambers40 are formed in the wall 38. Reciprocably disposed within each of thechambers 40 is a magnetic device 42. The magnetic devices 42 arerepresentatively illustrated in FIG. 2 as including multiple stackeddisk shaped permanent magnets 44, but other types of magnetic devicesmay be used if desired.

The magnetic devices 42 are magnetically coupled to another magneticdevice 46 attached to the operating member 26. The magnetic device 46 isdepicted in FIG. 2 as including multiple stacked annular shapedpermanent magnets 48, but other types of magnetic devices may be used ifdesired.

A resulting magnetic coupling force between the magnetic devices 42, 46causes the magnetic devices to displace together, i.e., displacement ofthe magnetic device 46 is fixed to displacement of the magnetic devices42. As described more fully below, an actuator of the safety valve 12 isused to displace the magnetic devices 42, and thereby displace themagnetic device 46 and the attached operating member 26, to operate thesafety valve.

A somewhat enlarged scale cross-sectional view of the safety valve 12 isrepresentatively illustrated in FIG. 3. In this view the manner in whichthe chambers 40 and magnetic devices 42 are circumferentially spacedapart in the housing wall 38 may be clearly seen. The housing wall 38 ispreferably made of a non-magnetic material, so that it does notinterfere with the magnetic coupling between the magnetic devices 42,46.

Note that the housing wall 38 is more structurally rigid and morecapable of resisting the pressure differential between the passage 22and the wellbore 20 exterior to the safety valve 12, as compared to theuse of separate walls to separately resist these pressure differentials.This due in part to the wall 38 being radially thicker in those portionsof the wall which completely surround the chambers 40 and magneticdevices 42.

Because of this increased structural integrity of the wall 38, themagnetic devices 42 can be positioned relatively close to the magneticdevice 46, thereby increasing the magnetic coupling force between themagnetic devices 42, 46. Although twenty-four of the magnetic devices 42are depicted in FIG. 3, greater or lesser numbers of the magneticdevices may be used in keeping with the principles of this disclosure.

Referring additionally now to FIG. 4, another cross-sectional view ofthe safety valve 12 is representatively illustrated, showing an actuator50 of the safety valve. It should be clearly understood, however, thatthe actuator 50 is described herein as only one example of manydifferent types of actuators which may be used in keeping with theprinciples of this disclosure. For example, various types of electrical,hydraulic, optical and other types of actuators may be used instead ofthe actuator 50.

The actuator 50 includes an annular piston 52 attached to each of themagnetic devices 42. The piston 52 is depicted in FIG. 4 as beingattached to the magnetic devices 42 using actuator members 54 in theform of rods interconnected between the piston and the magnetic devices,but other attachment methods may be used if desired.

Instead of an annular piston 52, one or more individual cylindricalpistons could be disposed in respective bores, and the piston(s) couldbe connected to a ring to which all of the members 54 are also attached.Thus, various different arrangements of pistons, members, etc., can beused in the actuator 50, and so the actuator is not limited at all toany of the details shown in the drawings and/or described herein.

Pressure is applied to displace the piston 52 by means of a port 56. Forexample, the line 18 illustrated in FIG. 1 could be connected to theport 56.

A pressure differential across the piston 52 may be applied to displacethe piston upwardly or downwardly to produce corresponding simultaneousdisplacement of the magnetic devices 42. This displacement of themagnetic devices 42 causes corresponding displacement of the magneticdevice 46 and operating member 26 to operate the safety valve 12.

To create a pressure differential across the piston 52, a lower side ofthe piston may be in fluid communication with the flow passage 22, withthe wellbore 20 external to the safety valve, with another line, with apressure chamber in the safety valve, etc. Thus, it will be appreciatedthat many different ways of constructing the actuator 50 may be used inkeeping with the principles of this disclosure.

Referring additionally now to FIG. 5, an enlarged scale side view of oneof the magnetic devices 42 is representatively illustrated apart fromthe remainder of the safety valve 12. In this view it may be seen thatthe magnetic device 42 may include rollers 58 or any other type offriction reducing device in order to reduce the force required todisplace the magnetic devices in the chambers 40.

Referring additionally now to FIG. 6, a schematic cross-sectional viewof an alternate configuration of the safety valve 12 is representativelyillustrated. This cross-sectional view is very similar to thatillustrated in FIG. 3, except that the housing 36 has been modified inthe FIG. 6 embodiment.

The housing wall 38 in the FIG. 6 embodiment includes an inner wall 38 aand an outer wall 38 b. This configuration makes manufacturing of thehousing 36 more convenient, since the chambers 40 can be formed bymilling longitudinal recesses in the exterior of the inner wall 38 a(for example, using a ball end mill, etc.), and then radially outwardlyclosing off the recesses with the outer wall 38 b. The inner and outerwalls 38 a, 38 b may be joined to each other above and below thechambers 40 by various methods, such as threading, welding, etc.

The inner and outer walls 38 a, 38 b still resist the pressuredifferential between the passage 22 and the exterior of the safety valve12. The inner and outer walls 38 a, 38 b can support each other inresisting this pressure differential due to structural supports 60between the chambers 40 which provide engagement between the inner andouter walls.

The supports 60 are depicted in FIG. 6 as being integrally formed withthe inner wall 38 a, but the supports could also, or alternatively, beformed as part of the outer wall 38 b (for example, the chambers 40could be formed partially on the inner wall and partially in the outerwall). As another alternative, the supports 60 could be formed separatefrom both of the inner and outer walls 38 a, 38 b. In the alternativedepicted in FIG. 3, the supports 60 are integrally formed as part of thewall 38.

Referring additionally now to FIG. 7, an enlarged scale schematicquarter-sectional view of the safety valve 12 is representativelyillustrated. This view is similar to the view of FIG. 2, but at a largerscale so that an arrangement of the magnetic devices 42, 46 may be moreclearly seen.

As depicted in FIG. 7, the magnets 44 in each magnetic device 42 arearranged with their poles longitudinally aligned, and with similar polesof adjacent magnets facing each other. That is, the positive (+) polesface each other, and the negative (−) poles face each other.

The annular magnets 48 of the magnetic device 46 are arranged with theirpoles radially aligned, and with the poles alternating longitudinallyalong the magnetic device. That is, one magnet 48 will have a positivepole facing radially outward and a negative pole facing radially inward,and an adjacent magnet will have a negative pole facing radially outwardand a positive pole facing radially inward.

Each radially outward facing positive pole of the magnetic device 46 isaligned with an interface between two facing negative poles of themagnetic device 42, and each radially outward facing negative pole ofthe magnetic device 46 is aligned with an interface between two facingpositive poles of the magnetic device 42.

The operating member 26 is preferably made of a ferromagnetic material,which acts to concentrate the magnetic flux due to the magnets 48. Thehousing 36 in this embodiment is preferably made of a non-magneticmaterial.

Referring additionally now to FIG. 8, a quarter-sectional view of analternate arrangement of the magnetic devices 42, 46 is representativelyillustrated. In this embodiment, the housing 36 includes inner and outerwalls 38 a, 38 b, as in the embodiment of FIG. 6, with the outer wall 38b being made of a ferromagnetic material and the inner wall 38 a beingmade of a non-magnetic material.

The magnets 48 of the magnetic device 46 are arranged similar to theFIG. 7 embodiment, but the magnets 44 of the magnetic device 42 havetheir poles radially, instead of longitudinally, aligned. Each radiallyinward facing positive pole of the magnets 42 now is aligned with aradially outward facing negative pole of the magnets 48, and eachradially inward facing negative pole of the magnets 42 is now alignedwith a radially outward facing positive pole of the magnets 48.

The ferromagnetic outer housing wall 38 b acts to concentrate themagnetic flux due to the magnets 44. In addition, this configuration isexpected to reduce friction in displacing the magnetic devices 42through the chambers 40.

Referring additionally now to FIG. 9, a quarter-sectional view ofanother alternate arrangement of the magnetic devices 42, 46 isrepresentatively illustrated. In this embodiment, the housing 36includes inner and outer walls 38 a, 38 b, as in the embodiment of FIG.8, but the outer wall 38 b and the inner wall 38 a are both made of anon-magnetic material.

The magnets 44, 48 are arranged as in the embodiment of FIG. 8, but eachmagnetic device 42 further includes a flux attractor 62 radiallyoutwardly adjacent the magnets 44. The flux attractor 62 is preferablymade of a ferromagnetic material, and acts to concentrate the flux dueto the magnets 44. Instead of a single flux attractor 62 in eachmagnetic device 42, a separate ferromagnetic backing could be providedfor each magnet 44, if desired.

Note that the magnetic device 42 of FIG. 9 could be used in place of themagnetic device 42 of FIG. 7. Stated differently, the inner and outerwalls 38 a, 38 b of FIG. 9 could be replaced by the wall 38 of FIG. 7.

Referring additionally now to FIGS. 10A-G, another configuration of thesafety valve 12 is representatively illustrated. In this configuration,the magnetic devices 42 are connected to the operating member 26, andthe magnetic device 46 is displaced by the actuator 50.

The actuator 50 in this example includes multiple pistons 52, each ofwhich is reciprocably received in one of a series of circumferentiallyspaced apart and longitudinally extending bores 66. The bores 66 areformed in the wall 38 of the housing 36 which resists a pressuredifferential between the interior and the exterior of the safety valve12. Any number of pistons 52 (including one) may be used in keeping withthe scope of this disclosure.

The pistons 52 are connected to a sleeve 68. The sleeve 68 is biasedupwardly (as viewed in the figures) by a biasing device 70 (such as acoiled spring, compressed gas chamber, etc.). The sleeve 68 is connectedto the magnetic device 46, which is magnetically coupled to the magneticdevices 42.

When increased pressure is applied to the port 56, the pistons 52displace downwardly, thereby also displacing the sleeve 68 and magneticdevice 46 downwardly against the biasing force exerted by the biasingdevice 70. The magnetic device 46 is magnetically coupled to themagnetic devices 42 and, thus, displace together. Since the magneticdevices 42 are connected to the operating member 26, the operatingmember and the magnetic devices 42 also displace downward, therebypivoting the flapper 28 to its open position.

In this example, the pistons 52 are exposed to a pressure differentialbetween the port 56 and the exterior of the safety valve 12. However, inother examples, the pistons 52 could be exposed to a pressuredifferential between the port 56 and the interior flow passage 22, apressurized gas chamber, or other pressure source.

The magnetic devices 42 are disposed in the chambers 40 in the housingwall 38. Preferably, the magnetic devices 42 are circumferentiallyspaced apart, but it is not necessary for the spacing to be equal. Forexample, the magnetic devices 42 could be unequally spaced apart oreccentered in the housing wall 38 for various purposes, such as, toprovide space for extending lines, power springs, etc. (not shown)through the wall.

In the example of FIGS. 10A-G, the housing wall 38 could be formed froma single piece of material, or it may be comprised of multiple separatepieces of material, as in the example of FIG. 6. Supports 60 (notvisible in FIGS. 10A-G, see FIGS. 3 & 6) are preferably provided toresist pressure applied from the interior and/or exterior of the safetyvalve 12.

Although in the above examples of FIGS. 4-10G, the actuator 50 ispressure operated, in other examples the actuator could be electrically,optically or otherwise actuated. For example, a motor and ball screw, ora linear induction motor, or another type of actuator may be used. Theactuator 50 is not necessarily concentric with the passage 22, but couldinstead be eccentered (off-center), provided in a “pocket” on a side ofthe safety valve 12, or otherwise disposed.

It may now be fully appreciated that the principles of this disclosureenable the safety valve 12 to be constructed in a manner which providesincreased magnetic coupling force, as well as increased pressureresisting capability.

The above disclosure describes a safety valve 12 which, in one example,includes the housing 36 having multiple chambers 40 extendinglongitudinally in the pressure bearing wall 38 of the housing. Each ofthe magnetic devices 42 is reciprocably disposed in a corresponding oneof the chambers 40.

The housing wall 38 is preferably made of a non-magnetic material. Thechambers 40 and magnetic devices 42 are circumferentially spaced apartin the housing wall 38. Each of the magnetic devices 42 is completelysurrounded by the housing wall 38.

The housing wall 38 may be made up of multiple components, such as innerand outer walls 38 a, 38 b. Structural supports 60 between the chambers40 may provide contact between the inner and outer walls 38 a, 38 b toenhance the capability of resisting the pressure differential betweenthe passage 22 and the exterior of the safety valve 12. For example, thesupports 60 can transmit force from the outer wall 38 b to the innerwall 38 a due to pressure exerted external to the safety valve 12, andthe supports can transmit force from the inner wall to the outer walldue to pressure exerted within the passage 22.

The magnetic devices 42 are magnetically coupled to the magnetic device46 attached to the operating member 26 of the safety valve 12. Theactuator 50 simultaneously displaces the magnetic devices 42 in thechambers 40. The annular piston 52 of the actuator 50 is connected toeach of the magnetic devices 42.

Also described above is an example of a safety valve 12 which caninclude multiple first magnetic devices 42 reciprocably disposed inrespective longitudinally extending chambers 40, and a second magneticdevice 46 magnetically coupled to the first magnetic devices 42. Thefirst magnetic devices 42 are circumferentially spaced apart and areencircled by the second magnetic device 46.

The first magnetic devices 42 can be attached to an operating member 26of the safety valve 12.

The safety valve 12 can also include a housing 36 having a pressurebearing wall 38, with the chambers 40 extending in the housing wall 38.The housing wall 38 may be made of a non-magnetic material. Each of thefirst magnetic devices 42 may be completely surrounded by the housingwall 38.

The housing wall 38 may be exposed to pressure in an interiorlongitudinal passage 22 formed through the safety valve 12. At least onesupport 60 can be positioned between the chambers 40 to resist pressurein an interior longitudinal passage 22 formed through the safety valve12.

An actuator 50 of the safety valve 12 may simultaneously displace thefirst magnetic devices 42.

The above disclosure also describes a safety valve 12 which, in oneexample, can include multiple longitudinally extending chambers 40 andmultiple first magnetic devices 42. Each of the first magnetic devices42 may be reciprocably disposed in a respective one of the chambers 40,and the first magnetic devices 42 may be attached to an operating member26 of the safety valve 12.

It is to be understood that the various examples described above may beutilized in various orientations, such as inclined, inverted,horizontal, vertical, etc., and in various configurations, withoutdeparting from the principles of this disclosure. The embodimentsillustrated in the drawings are depicted and described merely asexamples of useful applications of the principles of the disclosure,which are not limited to any specific details of these embodiments.

In the above description of the representative examples, directionalterms (such as “above,” “below,” “upper,” “lower,” etc.) are used forconvenience in referring to the accompanying drawings. In general,“above,” “upper,” “upward” and similar terms refer to a direction towardthe earth's surface along a wellbore, and “below,” “lower,” “downward”and similar terms refer to a direction away from the earth's surfacealong the wellbore, whether the wellbore is horizontal, vertical,inclined, deviated, etc. However, it should be clearly understood thatthe scope of this disclosure is not limited to any particular directionsdescribed herein.

Of course, a person skilled in the art would, upon a carefulconsideration of the above description of representative embodiments,readily appreciate that many modifications, additions, substitutions,deletions, and other changes may be made to these specific embodiments,and such changes are within the scope of the principles of thisdisclosure. Accordingly, the foregoing detailed description is to beclearly understood as being given by way of illustration and exampleonly, the spirit and scope of the invention being limited solely by theappended claims and their equivalents.

What is claimed is:
 1. A safety valve for use in a subterranean well,the safety valve comprising: multiple first magnetic devices whichreciprocate within respective longitudinally extending chambers; asecond magnetic device magnetically coupled to the first magneticdevices; and wherein the first magnetic devices are circumferentiallyspaced apart and are encircled by the second magnetic device.
 2. Thesafety valve of claim 1, wherein the first magnetic devices are attachedto an operating member of the safety valve.
 3. The safety valve of claim1, further comprising a housing having a pressure bearing wall, andwherein the chambers extend in the housing wall.
 4. The safety valve ofclaim 3, wherein the housing wall is made of a non-magnetic material. 5.The safety valve of claim 3, wherein each of the first magnetic devicesis completely surrounded by the housing wall.
 6. The safety valve ofclaim 3, wherein the housing wall is exposed to pressure in an interiorlongitudinal passage formed through the safety valve.
 7. The safetyvalve of claim 3, wherein at least one support positioned between thechambers resists pressure in an interior longitudinal passage formedthrough the safety valve.
 8. The safety valve of claim 1, wherein anactuator of the safety valve simultaneously displaces the first magneticdevices.
 9. A safety valve for use in a subterranean well, the safetyvalve comprising: multiple longitudinally extending chambers, thechambers being circumferentially spaced apart; and multiple firstmagnetic devices attached to an operating member of the safety valve,wherein each of the first magnetic devices reciprocates within arespective one of the chambers.
 10. The safety valve of claim 9, whereinthe first magnetic devices are magnetically coupled to a second magneticdevice which encircles the first magnetic devices.
 11. The safety valveof claim 9, wherein an actuator of the safety valve simultaneouslydisplaces the first magnetic devices within the chambers.
 12. The safetyvalve of claim 9, wherein at least one support positioned between thechambers resists pressure in an interior longitudinal passage formedthrough the safety valve.
 13. The safety valve of claim 9, wherein thechambers are disposed in a housing wall of the safety valve.
 14. Thesafety valve of claim 13, wherein the housing wall is made of anon-magnetic material.
 15. The safety valve of claim 13, wherein thechambers and the first magnetic devices are circumferentially spacedapart in the housing wall.
 16. The safety valve of claim 13, whereineach of the first magnetic devices is completely surrounded by thehousing wall.
 17. The safety valve of claim 13, wherein the housing wallis exposed to pressure in an interior longitudinal passage formedthrough the safety valve.